Four spontaneous, single-step mutants of Escherichia coli K-12 resistant to low levels of the cephalosporin 3'-quinolone ester Ro 23-9424 were isolated at a frequency of 10(-10) to 10(-11) mutants per CFU plated. The mutants were cross-resistant to both cephalosporin (cefotaxime) and quinolone (fleroxacin) components. Accordingly, they had altered porins and replicative DNA biosynthesis resista...

Two divergent synthetic routes are reported offering access to four quinolone natural products from Pseudonocardia sp. CL38489. Key steps to the natural products involved a regioselective epoxidation, an intramolecular Buchwald-Hartwig amination and a final acid-catalysed 1,3-allylic-alcohol rearrangement to give two of the natural products in one step. This study completes the synthesis of all...

Irloxacin and E-3846 are two new fluorinated quinolones. We evaluated the activities of these antimicrobial agents, ciprofloxacin, ofloxacin, enoxacin, pefloxacin, norfloxacin, and nalidixic acid against 1,161 bacterial strains. Ciprofloxacin was the most active quinolone. Irloxacin did not show great activity. The activity of E-3846 against gram-negative bacteria was similar to those of ofloxa...

Antipneumococcal activity of BMS 284756 was compared to those of six agents by MIC and time-kill methodologies. BMS 284756 had the lowest MICs compared to those of ciprofloxacin, levofloxacin, and moxifloxacin against quinolone-susceptible (< or =0.016 to 0.06 microg/ml) and quinolone-resistant (0.03 to 1 microg/ml) pneumococci. BMS 284756 was bactericidal against 11 of 12 strains at two times ...

A new magnesium complex of quinolone antibacterial agent was prepared. This new complex as well as a previously isolated complex of magnesium with ciprofloxacin were tested against various Gram positive and Gram negative microorganisms. Antimicrobial activities were evaluated using the agar diffusion test. The results have shown that all magnesium complexes are significantly less active than th...

In order to study the interactions between Escherichia coli DNA gyrase and the gyrase interacting protein QnrB in vivo, we constructed a gyrB-gyrA fusion and validated its ability to correct the temperature-sensitive growth of gyrA and gyrB mutants. Like wild-type gyrA, the gyrB-gyrA fusion complemented a quinolone-resistant gyrA mutant to increase susceptibility. It functioned as an active typ...

Plasmid toxins CcdB and ParE are part of addiction systems promoting plasmid maintenance. Both target host DNA gyrase, as do quinolones and plasmid-determined Qnr proteins that protect gyrase from quinolone inhibition. We cloned qnrB4, qnrS1, ccdB, parE, and the antitoxin-encoding genes ccdA and parD on compatible plasmids and tested them in combination. CcdB and ParE had no specific effect on ...

The gyrA quinolone resistance determining region was sequenced from 13 ciprofloxacin-resistant and 20 ciprofloxacin-susceptible Campylobacter jejuni isolates. All isolates resistant to ciprofloxacin had Thr-86-to-Ile mutations, a mutation frequently associated with the acquisition of resistance to fluoroquinolones. A mismatch amplification mutation assay (MAMA) PCR protocol was developed that d...

Vibrio anguillarum is a Gram-negative commashaped bacterium with polar flagella that is a member of the family Vibrionaceae. It is the cause of vibriosis or haemorrhagic septicaemic disease in wild and cultured marine and freshwater fish (Actis, Tolmasky & Crosa 1999; Austin & Austin 1999). Chemotherapeutic agents, including quinolones, have been widely used for the treatment of vibriosis in cu...

For Staphylococcus aureus, stepwise mutations result in high-level quinolone resistance. Methicillin-resistant and -susceptible quinolone-resistant, first-step mutants generated in vitro were obtained and found to be no different than those recovered from murine abscesses. Approximately 10% of all first-step mutants were resistant to ethidium bromide, and selected strains had mutations that map...